This invention relates to bone graft materials.
Bone grafting is a common procedure in orthopaedic practice. There is little doubt that at present the most effective osseous graft material available is fresh autologous bone. However the source of supply is limited and in most cases an additional surgical exposure is necessary to obtain the graft. The use of foreign material (implant) has therefore advantages for both patient and surgeon. Many types of foreign material have been suggested in the past.
Porous materials have been shown to allow the ingrowth of living tissue and this fact is made use of in clinical situations. For example polyester or polytetrafluoroethylene weaves are used to replace blood vessels. At present, porous ceramics and rigid polymers are being tested in an attempt to attach artificial teeth to the alveolar ridge.
Excellent biocompatibility has been demonstrated in various animals to vitreous carbon (Kenner et al., J. Biomed. Mat. Res. 9 111), graphite filaments reinforced with epoxy resins (Musikant, J. Biomed. Mat. Res. 1 225), powdered carbon (Bechtol et al., "Metals and Engineering in Bone and Joint Surgery", Williams and Wilkins, Baltimore, 1959), porous carbon (Stanitski et al., Clemson University Symposium, Clemson S.C., U.S.A. 1972), and solid carbon (Mooney et al., J. Biomed. Mat. Res. 5 143). Recently, filamentary carbon developed from polyacrylonitrile and developed at the Royal Aircraft Establishment, Farnborough, U.K. has been used to repair tendons in rabbits and sheep (Jenkins et al., J. Bone & Joint Surgery, 59B,No. 1, 53).
The use of porous implants in orthopaedics has been almost exclusively directed to the aim of achieving permanent attachment of prostheses to bone, thus most work has been conducted with high strength materials (e.g. porous ceramics or metals). Research into porous carbon has been conducted (e.g. Cestero et al., J. Biomed. Mat. Res., Symposium No. 6, 1, 1975), but the aim has also been to attach material or prostheses to bone.
The known carbon implants arise from synthetic forms of carbon. Moreover, there appears to have been no previous thought given to the use of a porous implant to repair a skeletal defect (thus acting as a bone substitute). I have considered that implants prepared from a natural source of carbon may have advantages over these known synthetic forms, and especially for skeletal defect repair.